Vascular bundles (VBs) is a strand of conducting
vessels in the stem or leaves of a plant, typically with
phloem on the outside and xylem on the inside. In the
given figures A, B and C the types of vascular bundles are
respectively radial, conjoint closed and conjoint open.
When xylem and phloem are arranged in the radius of the
plant in alternative manner then it is called radial vascular
bundle. Radial VBs are always closed and present in all
types of roots. In conjoint vascular bundle, xylem and
phloem are situated at the same radius of vascular bundles.
Such VBs are common in stems and leaves.